Colorectal, Anorectal & Pilonidal Disease

In non-metastatic, locally advanced (radiologically high-risk cT3 and/or cN+) dMMR colon adenocarcinoma, give short-course neoadjuvant dual immune checkpoint blockade — two 28-day cycles: nivolumab 3 mg/kg + ipilimumab 1 mg/kg on day 1, followed by nivolumab 3 mg/kg on day 15 — followed by scheduled surgical colectomy within 6 weeks of enrolment, within multidisciplinary oncology pathways. Universal pre-treatment MMR/MSI testing on colon biopsy specimens is the entry step.

Before: Locally advanced colon cancer proceeded directly to colectomy, with MMR/MSI status not routinely established on the pre-treatment biopsy and no neoadjuvant immunotherapy in the pathway (converse of the book's printed practice implication — §1.3 appraisals print no outdated-routine cell).

Now: In non-metastatic, locally advanced (radiologically high-risk cT3 and/or cN+) dMMR colon adenocarcinoma, give short-course neoadjuvant dual immune checkpoint blockade — two 28-day cycles: nivolumab 3 mg/kg + ipilimumab 1 mg/kg on day 1, followed by nivolumab 3 mg/kg on day 15 — followed by scheduled surgical colectomy within 6 weeks of enrolment, within multidisciplinary oncology pathways. Universal pre-treatment MMR/MSI testing on colon biopsy specimens is the entry step.

Patients with non-metastatic, locally advanced dMMR colon adenocarcinoma. NICHE-2 enrolled radiologically high-risk cT3 and/or cN+ disease (n = 115 enrolled; 111 in the efficacy population; 67% sporadic dMMR, 33% Lynch syndrome).

NICHE-2 results: 98% of patients (113/115) underwent timely R0 colectomy; pathological response 98% (<=50% residual viable tumor), major pathological response 95% (<=10% residual viable tumor), pathological complete response 68% (95% CI 58%–76%); disease recurrence 0% at median 26-month follow-up; Grade 3 or 4 immune-related adverse events in 4% (5/115). The design is non-randomized single-arm Phase II: NICHE-2 evaluates pathological response at colectomy and does NOT establish non-operative organ preservation in colon cancer; mature 3-year survival and Phase III randomized data (e.g., AZUR-2) are pending. Preoperative CT restaging frequently underestimates pathological response. Do not conflate this evidence base with the separate dostarlimab rectal-cancer cohort.

• NICHE-2 — Chalabi M et al., N Engl J Med 2024 (PMID 38838311; Ref. 9)

Test MMR/MSI on every diagnostic rectal biopsy. In mismatch repair-deficient (dMMR) Stage II or Stage III rectal adenocarcinoma, single-agent intravenous dostarlimab (anti-PD-1 monoclonal antibody, 500 mg every 3 weeks for 6 months [9 cycles]) can be followed — when a clinical complete response (cCR) is achieved — by non-operative watch-and-wait surveillance omitting chemoradiotherapy and total mesorectal excision. Non-operative management after PD-1 blockade is restricted to specialized multidisciplinary centers or clinical trials with rigorous every-3-to-4-month endoscopic, digital, and pelvic MRI surveillance.

Before: Locally advanced rectal cancer proceeded to fluoropyrimidine-based chemoradiotherapy and total mesorectal excision, with MMR/MSI status not routinely established on the diagnostic biopsy (converse of the book's printed practice implication — §1.3 appraisals print no outdated-routine cell).

Now: Test MMR/MSI on every diagnostic rectal biopsy. In mismatch repair-deficient (dMMR) Stage II or Stage III rectal adenocarcinoma, single-agent intravenous dostarlimab (anti-PD-1 monoclonal antibody, 500 mg every 3 weeks for 6 months [9 cycles]) can be followed — when a clinical complete response (cCR) is achieved — by non-operative watch-and-wait surveillance omitting chemoradiotherapy and total mesorectal excision. Non-operative management after PD-1 blockade is restricted to specialized multidisciplinary centers or clinical trials with rigorous every-3-to-4-month endoscopic, digital, and pelvic MRI surveillance.

Patients with dMMR, Stage II or Stage III rectal adenocarcinoma — dMMR disease is ~5%–10% of rectal cancers. Response is assessed by rectal MRI, high-definition endoscopy, and digital rectal examination (the trial also used 18F-FDG PET and endoscopic biopsy).

Among the 12 consecutive patients who completed 6 months of dostarlimab and had at least 6 months of follow-up (median 12 months; range 6–25), all 12 (100%; 95% CI 74%–100%) achieved a clinical complete response, with 0% requiring chemoradiotherapy or surgery during reported follow-up and no Grade 3 or higher adverse events in the initial 16 patients. But the sample is very small (n = 12 completing therapy in the primary report), the design single-center and non-randomized, follow-up short, and the endpoint clinical (cCR) rather than pathological (pCR) response — these early non-randomized findings must not be equated with mature Phase III comparative evidence. Do not conflate this evidence base with the separate NICHE-2 colon-cancer cohort.

• MSKCC Dostarlimab Trial — Cercek A et al., N Engl J Med 2022 (PMID 35660797; Ref. 10)

Give intraoperative intravenous indocyanine green near-infrared fluorescence perfusion angiography before and/or after the colorectal anastomosis — commonly 0.1–0.2 mg/kg or a 2.5–5 mg bolus, with near-infrared excitation (~800–830 nm) visualizing serosal perfusion within 45–60 seconds (§1.4) — and be prepared to change the planned proximal colonic transection line (prompted in ~7%–10.6% of patients). The book supports near-infrared ICG perfusion angiography as a safe intraoperative optical adjunct during minimally invasive rectal cancer resection (Conditional recommendation; Moderate certainty).

Before: Anastomotic perfusion assessed by standard white-light surgeon assessment alone before completing a colorectal anastomosis (the comparator the two trials randomized against, as printed in §1.3 Trial 1.7).

Now: Give intraoperative intravenous indocyanine green near-infrared fluorescence perfusion angiography before and/or after the colorectal anastomosis — commonly 0.1–0.2 mg/kg or a 2.5–5 mg bolus, with near-infrared excitation (~800–830 nm) visualizing serosal perfusion within 45–60 seconds (§1.4) — and be prepared to change the planned proximal colonic transection line (prompted in ~7%–10.6% of patients). The book supports near-infrared ICG perfusion angiography as a safe intraoperative optical adjunct during minimally invasive rectal cancer resection (Conditional recommendation; Moderate certainty).

Adults undergoing elective left-sided colectomy or low anterior resection with an anastomosis <=10 cm from the anal verge (PILLAR III population) and adults with clinical Stage I–III rectal carcinoma undergoing minimally invasive (laparoscopic or robotic) sphincter-preserving rectal resection (EssentiAL population).

PILLAR III was neutral on its primary endpoint: 30-day anastomotic leak 9.0% (16/178) with ICG vs. 9.6% (16/169) with standard assessment (absolute difference −0.6%; p = 0.84), in a trial terminated early at n = 347. EssentiAL (n = 839 modified ITT) found Clavien–Dindo Grade >=II leak significantly lower with ICG: 7.6% (32/422) vs. 11.8% (49/417; risk ratio 0.64, 95% CI 0.42–0.98; absolute risk reduction 4.2 percentage points; p = 0.041), with Grade >=III leaks requiring re-intervention 4.7% vs. 8.2% (p = 0.044). The trials differed substantially in population, statistical power, diverting stoma utilization, and endpoint grading; visual ICG assessment remains qualitative rather than quantitatively standardized — not every colorectal resection will experience the same magnitude of leak reduction.

Product-label caution (§1.4): indocyanine green for injection contains trace sodium iodide and is contraindicated in patients with documented hypersensitivity to indocyanine green or sodium iodide according to the locally approved product label — verify product-specific labeling, and do not conflate a vague history of seafood or iodinated contrast reaction with documented ICG/iodide anaphylaxis, while maintaining standard resuscitation readiness.

• PILLAR III — Jafari MD et al., Dis Colon Rectum 2021 (PMID 33872284; Ref. 11)
• EssentiAL — Watanabe J et al., Ann Surg 2023 (PMID 37218517; Ref. 12)

In physiologically fit adults, perform laparoscopic ventral mesh rectopexy (LVMR), or laparoscopic resection rectopexy if severe slow-transit constipation is present. In frail/high-risk elderly patients, use a perineal repair — Delorme mucosal sleeve resection for short prolapse <5 cm, or Altemeier perineal rectosigmoidectomy for longer prolapse.

Before: Uniform perineal resection or open posterior suture rectopexy, with high constipation and recurrence rates.

Now: In physiologically fit adults, perform laparoscopic ventral mesh rectopexy (LVMR), or laparoscopic resection rectopexy if severe slow-transit constipation is present. In frail/high-risk elderly patients, use a perineal repair — Delorme mucosal sleeve resection for short prolapse <5 cm, or Altemeier perineal rectosigmoidectomy for longer prolapse.

Adults with full-thickness rectal prolapse (procidentia) — physiologically fit adults vs. frail elderly patients, exactly as the addendum's summary row stratifies them.

Abdominal autonomic-nerve-sparing rectopexy yields lower long-term recurrence (~3–8% vs. 15–25% perineal), whereas perineal approaches avoid general anesthesia and laparotomy in frail patients — the recurrence advantage does not override frailty in the elderly group.

• ASCRS Rectal Prolapse Clinical Practice Guidelines — as cited in the addendum summary table (no PMID printed)
• PROSPER Trial — as cited in the addendum summary table (no PMID printed)

For sigmoid volvulus without ischemia or perforation: flexible endoscopic detorsion (75–90% success) followed by same-admission elective sigmoid colectomy. For Ogilvie's syndrome (acute colonic pseudo-obstruction, cecal diameter >=10–12 cm without perforation): stop opioids and anticholinergics, correct K+ and Mg2+, and administer IV neostigmine (2.0–2.5 mg slow IV with cardiac telemetry and atropine at the bedside) or perform colonoscopic decompression.

Before: Blind rigid rectal tube decompression alone without definitive surgery, or immediate laparotomy without endoscopic decompression in non-gangrenous volvulus.

Now: For sigmoid volvulus without ischemia or perforation: flexible endoscopic detorsion (75–90% success) followed by same-admission elective sigmoid colectomy. For Ogilvie's syndrome (acute colonic pseudo-obstruction, cecal diameter >=10–12 cm without perforation): stop opioids and anticholinergics, correct K+ and Mg2+, and administer IV neostigmine (2.0–2.5 mg slow IV with cardiac telemetry and atropine at the bedside) or perform colonoscopic decompression.

Patients with acute uncomplicated sigmoid volvulus (no ischemia or perforation) and patients with acute colonic pseudo-obstruction (Ogilvie's syndrome) with cecal diameter >=10–12 cm and no perforation, exactly as the addendum's summary row states them.

Endoscopic detorsion alone in sigmoid volvulus carries a 45–70% recurrence rate with high mortality on readmission — decompression without same-admission definitive surgery is not the standard. IV neostigmine resolves >80% of refractory Ogilvie's syndrome within 30 minutes; it is given with cardiac telemetry and atropine at the bedside, as printed.

• ASCRS / WSES Volvulus & Colonic Pseudo-Obstruction Guidelines — as cited in the addendum summary table (no PMID printed)

Adequate incision and drainage positioned off the midline over the fluctuant collection when anatomically feasible to avoid a problematic deep midline wound, with curettage of hair/debris; base systemic antibiotic use on clinical presentation (surrounding cellulitis, systemic sepsis) and patient risk profile (such as poorly controlled diabetes or immunosuppression). Published techniques describe placing the incision roughly 1.5–2.0 cm lateral to the midline over the fluctuant cavity (§2.2 prose). Antibiotic decisions follow the presentation and the patient's overall risk profile rather than a mechanical rule based on the label of diabetes alone (§2.0 Guardrail 3).

Before: Placing a longitudinal drainage incision directly in the deep midline natal cleft and prescribing routine multi-day oral antibiotics for every drained abscess regardless of clinical presentation.

Now: Adequate incision and drainage positioned off the midline over the fluctuant collection when anatomically feasible to avoid a problematic deep midline wound, with curettage of hair/debris; base systemic antibiotic use on clinical presentation (surrounding cellulitis, systemic sepsis) and patient risk profile (such as poorly controlled diabetes or immunosuppression). Published techniques describe placing the incision roughly 1.5–2.0 cm lateral to the midline over the fluctuant cavity (§2.2 prose). Antibiotic decisions follow the presentation and the patient's overall risk profile rather than a mechanical rule based on the label of diabetes alone (§2.0 Guardrail 3).

Patients presenting with an acute fluctuant sacrococcygeal pilonidal abscess. Outcomes rated in the matrix: abscess resolution, wound healing, and antimicrobial stewardship.

Drainage incisions positioned lateral to the deep intergluteal sulcus avoid creating a high-shear midline wound; systemic antibiotics do not improve healing of adequately drained uncomplicated abscesses in low-risk hosts, whereas cellulitis, systemic illness, or host immunocompromise lowers the threshold for antimicrobial therapy (matrix rationale). When infiltrating local anesthetics (lidocaine and/or bupivacaine with or without epinephrine), calculate weight-based maximum cumulative doses — accounting for additive local-anesthetic toxicity when combining amides — and verify institutional dosing safeguards (§2.0 Guardrail 3).

No standalone Saudi/GCC pilonidal guideline is separately published (§2.2 regional frame); the chapter's framework draws on international society guidance and published Saudi clinical data rather than representing an official national pathway.

• ASCRS 2019 Pilonidal Guideline — Johnson et al. (PMID 30640830)
• German S3 Guideline (2020/2021) & ESCP 2024 Guideline — as cited in Table 2.1

Provide general gluteal cleft hygiene counseling and hair control; consider adjunctive medical laser epilation in eligible adolescents and young adults with quiescent disease after discussing the single-center RCT evidence and its follow-up limitations. Distinguish general hair-control advice from the specific 5-session diode (810 nm) / Nd:YAG (1064 nm) laser epilation regimen the trial tested — it should not be presented as mandatory for all patients or as establishing a single universal laser device or session count (§2.2 prose). The book also records a guideline divergence: ASCRS 2019 permits regular gluteal cleft hair removal in the absence of acute abscess, while the German S3 guideline cautions that razor shaving may increase recurrence compared with atraumatic depilation or laser epilation (§2.2 prose).

Before: Omitting structured natal cleft hygiene counseling or presenting laser epilation as universally proven across all age groups and secondary outcomes.

Now: Provide general gluteal cleft hygiene counseling and hair control; consider adjunctive medical laser epilation in eligible adolescents and young adults with quiescent disease after discussing the single-center RCT evidence and its follow-up limitations. Distinguish general hair-control advice from the specific 5-session diode (810 nm) / Nd:YAG (1064 nm) laser epilation regimen the trial tested — it should not be presented as mandatory for all patients or as establishing a single universal laser device or session count (§2.2 prose). The book also records a guideline divergence: ASCRS 2019 permits regular gluteal cleft hair removal in the absence of acute abscess, while the German S3 guideline cautions that razor shaving may increase recurrence compared with atraumatic depilation or laser epilation (§2.2 prose).

Adolescents and young adults (aged 11–21 years) with quiescent pilonidal disease (the RCT population) and general chronic pilonidal patients (hygiene counseling). Outcomes rated in the matrix: 1-year recurrence, disability days, quality of life, and surgical re-intervention.

In Minneci et al. (n = 302 aged 11–21 years), 1-year recurrence was 10.4% (10/96) with adjunctive laser epilation vs. 33.6% (45/134) with standard care (absolute difference −23.2 percentage points, 95% CI −33.2 to −13.1; p < 0.001); however, 1-year outcome data were available for 63.6% of the laser group vs. 88.7% of the standard-care group, and no significant differences were shown in disability days, HRQOL, or surgical excisions. The matrix rates certainty Low when the result is extrapolated to older adults.

In the Riyadh tertiary-center cohort (§2.2 regional frame; Albabtain et al., n = 369), postoperative hair removal was inversely associated with recurrence (aOR 0.43, 95% CI 0.25–0.73) — a retrospective, observational association the book states must not be interpreted as proof that hair removal independently prevents recurrence. No standalone Saudi/GCC pilonidal guideline is separately published.

• Minneci et al. 2024 Laser Epilation RCT, JAMA Surg (PMID 37938854)
• ASCRS 2019 Pilonidal Guideline — Johnson et al. (PMID 30640830)
• Albabtain et al. 2021 Riyadh Tertiary Cohort (PMID 34085545)

First-line medical therapy for 6–8 weeks using topical calcium channel blockers (compounded 0.2%–0.5% nifedipine or 2% diltiazem ointment/gel BID–TID) or topical 0.2%–0.4% glyceryl trinitrate (GTN) ointment, with CCBs preferred due to lower headache incidence. LIS (tailored to the fissure apex or standard length) is reserved for medical failure in patients with normal baseline continence and low sphincter-injury risk, whereas botulinum toxin A injection or cutaneous V-Y advancement flap is preferred when continence risk is elevated.

Before: Upfront full-length lateral internal sphincterotomy (LIS) to the dentate line without prior first-line medical therapy or baseline continence risk assessment.

Now: First-line medical therapy for 6–8 weeks using topical calcium channel blockers (compounded 0.2%–0.5% nifedipine or 2% diltiazem ointment/gel BID–TID) or topical 0.2%–0.4% glyceryl trinitrate (GTN) ointment, with CCBs preferred due to lower headache incidence. LIS (tailored to the fissure apex or standard length) is reserved for medical failure in patients with normal baseline continence and low sphincter-injury risk, whereas botulinum toxin A injection or cutaneous V-Y advancement flap is preferred when continence risk is elevated.

Adults with chronic anal fissure (>6–8 weeks). Outcomes rated in the matrix: fissure healing at 6–8 weeks, headache adverse events, and long-term fecal incontinence.

Topical vasodilators achieve healing in ~65%–75% of chronic fissures, with headache falling from ~20%–30% (GTN) to <5%–10% with compounded nifedipine/diltiazem. LIS achieves >90%–95% healing, but continence risk depends on baseline continence, prior obstetric or anorectal injury, and anterior female sphincter anatomy — it is not a first step and not for elevated continence risk.

No standalone Saudi/GCC guideline for benign anorectal surgery is separately published; Saudi tertiary centres adopt ASCRS 2022–2024 guidance as an author-proposed regional adaptation (§1.2 regional frame, Tier 3).

• ASCRS 2023 Anal Fissure Guideline — Davids et al. (PMID 36321851)

Antibiotic omission may be considered for clinically stable, immunocompetent adults with CT-confirmed uncomplicated left-sided diverticulitis (WSES Stage 0), without systemic inflammation or evidence of complicated disease, who can tolerate oral intake and have reliable follow-up.

Before: Routine 7–10 day course of broad-spectrum oral or intravenous antibiotics for all patients with CT-proven uncomplicated diverticulitis, or conflating WSES Stage 0 with WSES Stage 1a.

Now: Antibiotic omission may be considered for clinically stable, immunocompetent adults with CT-confirmed uncomplicated left-sided diverticulitis (WSES Stage 0), without systemic inflammation or evidence of complicated disease, who can tolerate oral intake and have reliable follow-up.

Clinically stable, immunocompetent, nonpregnant adults with CT-confirmed WSES Stage 0 left-sided diverticulitis. Outcomes rated in the matrix: time to recovery, 24-month recurrence, complicated diverticulitis, and sigmoid resection.

Explicitly excluded (§1.0 Guardrail 1): patients with pericolic extraluminal gas or fluid (WSES Stage 1a), abscess (Stage 1b–2a), distant gas (Stage 2b), generalized peritonitis (Stage 3–4), pregnancy, sepsis, significant immunosuppression, frailty, or clinical deterioration — these require antibiotic and/or interventional escalation. DIABOLO (intention-to-treat, n = 528): no significant difference in time to recovery (14 days [IQR 6–29] vs. 12 days [IQR 7–30]; HR 0.91, 95% CI 0.76–1.09; p = 0.151), 24-month recurrent diverticulitis (15.4% vs. 14.9%), complicated diverticulitis (1.9% vs. 3.3%), or sigmoid resection (9.0% vs. 5.0%; p = 0.085).

No standalone Saudi/GCC diverticulitis guideline is separately published; Saudi tertiary centres adopt WSES 2020 guidance as an author-proposed regional adaptation (§1.2 regional frame, Tier 3).

• WSES 2020 Diverticulitis Guideline — Sartelli et al. (PMID 32381121)
• DIABOLO Trial — Daniels et al. (PMID 27686365)
• AVOD & DINAMO RCTs — as cited in Table 1.1

Fistulotomy is generally appropriate for selected simple, low fistulas in patients with acceptable baseline continence and no substantial sphincter vulnerability. For complex, high, recurrent, branching, or anatomically vulnerable fistulas (e.g., anterior fistula in women, prior sphincter injury, or Crohn disease), assess baseline continence and consider drainage with a loose seton followed by a sphincter-sparing procedure (LIFT or endorectal advancement flap); diode laser closure (FiLaC) is a conditional continence-preserving option.

Before: Using a single external anal sphincter (EAS) percentage cutoff (>30%) in isolation to mandate or exclude lay-open fistulotomy, or performing tight cutting-seton division in complex tracts.

Now: Fistulotomy is generally appropriate for selected simple, low fistulas in patients with acceptable baseline continence and no substantial sphincter vulnerability. For complex, high, recurrent, branching, or anatomically vulnerable fistulas (e.g., anterior fistula in women, prior sphincter injury, or Crohn disease), assess baseline continence and consider drainage with a loose seton followed by a sphincter-sparing procedure (LIFT or endorectal advancement flap); diode laser closure (FiLaC) is a conditional continence-preserving option.

Adults with simple low versus complex, high, anterior female, or recurrent cryptoglandular anal fistula. Outcomes rated in the matrix: primary fistula healing at 12–24 months and fecal continence preservation.

The proportion of EAS involved is one anatomical component of continence assessment, not an isolated threshold (§1.0 Guardrail 2). In selected cohorts after seton drainage, LIFT and advancement flaps achieve ~70%–78% healing at 12–24 months. FiLaC pooled primary healing was 67.3% (95% CI 56.8%–77.9%; I² ~68%, meta-analysis of 7 observational studies, n = 454) with ~1% minor continence change — a conditional option at low certainty, not the standard.

Author-proposed regional adaptation (§1.2 regional frame, Tier 3): before elective fistula reconstruction, heightened diagnostic evaluation to exclude perianal Crohn disease and intestinal tuberculosis (fecal calprotectin screening aid, ileocolonoscopy, pelvic MRI, and tissue AFB stain / M. tuberculosis PCR), and patient counselling against traditional caustic herbal pastes ('black ointment') applied to perianal abscesses or hemorrhoids.

• ASCRS 2022 Abscess & Fistula Guideline — Gaertner et al. (PMID 35732009)
• Elfeki et al. 2020 FiLaC Meta-Analysis (PMID 32065306)

After dietary fiber (25–35 g/day) and fluid optimization (flavonoids a conditional adjunct), office-based rubber band ligation (RBL) is the first procedural step. Office sclerotherapy (including 3% polidocanol foam) is a conditional option in selected anticoagulated patients with bleeding Grade I–II (and selected Grade III) internal hemorrhoids. Excisional hemorrhoidectomy is reserved for Grade IV, symptomatic external/mixed, or refractory Grade III disease.

Before: Upfront excisional hemorrhoidectomy (Milligan-Morgan or Ferguson) prior to office-based therapy, or treating single-session and repeat rubber band ligation (RBL) recurrence figures as identical.

Now: After dietary fiber (25–35 g/day) and fluid optimization (flavonoids a conditional adjunct), office-based rubber band ligation (RBL) is the first procedural step. Office sclerotherapy (including 3% polidocanol foam) is a conditional option in selected anticoagulated patients with bleeding Grade I–II (and selected Grade III) internal hemorrhoids. Excisional hemorrhoidectomy is reserved for Grade IV, symptomatic external/mixed, or refractory Grade III disease.

Adults with symptomatic Grade I–II or selected non-incarcerated Grade III internal hemorrhoids refractory to dietary fiber and fluid optimization. Outcomes rated in the matrix: 12-month symptom recurrence, early postoperative pain, and cost-effectiveness.

In HubBLe (n = 372, Grade II–early III), 1-year recurrence after a single RBL session was higher than after hemorrhoidal artery ligation (49% [87/176] vs. 30% [48/161]; adjusted OR 2.23, 95% CI 1.42–3.51; p = 0.0005); when planned repeat RBL (2 sessions) was counted, recurrence narrowed (37.5% vs. 30%; adjusted OR 1.35, 95% CI 0.85–2.15; p = 0.20) with lower day-1/day-7 pain and superior cost-effectiveness. Do not assume uninterrupted antithrombotic therapy has been validated across all drug regimens or advanced prolapsing grades.

No standalone Saudi/GCC guideline for benign anorectal surgery is separately published; Saudi tertiary centres adopt ASCRS 2022–2024 guidance as an author-proposed regional adaptation (§1.2 regional frame, Tier 3).

• ASCRS 2024 Hemorrhoids Guideline — Hawkins et al. (PMID 38294832)
• HubBLe RCT — Brown et al., Lancet 2016 (PMID 27236344)

Shared decision-making comparing minimally invasive approaches (pit-picking, trephine/Gips sinusectomy, diode laser ablation [SiLaC], EPSiT, or phenol/glue) with excisional options, matching choice to pit distribution, lateral extension, scarring, and patient preference regarding recovery vs. treatment failure. 'Limited' disease is defined descriptively — pit number and distribution, absence of wide lateral extension or complex branching tracts, and degree of scarring from previous procedures — never by a '1–4 midline pits' count treated as a validated cutoff (§2.2 prose).

Before: Performing wide excisional surgery in all primary cases without discussing minimally invasive, tissue-preserving alternatives and their durability trade-offs.

Now: Shared decision-making comparing minimally invasive approaches (pit-picking, trephine/Gips sinusectomy, diode laser ablation [SiLaC], EPSiT, or phenol/glue) with excisional options, matching choice to pit distribution, lateral extension, scarring, and patient preference regarding recovery vs. treatment failure. 'Limited' disease is defined descriptively — pit number and distribution, absence of wide lateral extension or complex branching tracts, and degree of scarring from previous procedures — never by a '1–4 midline pits' count treated as a validated cutoff (§2.2 prose).

Adolescents and adults with limited primary midline pilonidal disease (no extensive lateral scarring). Outcomes rated in the matrix: postoperative pain, complications, return to normal activities, and 6-month treatment failure.

In the prospective UK PITSTOP observational cohort (n = 667; 59.5% major excisional vs. 40.5% minimally invasive), minimally invasive procedures were associated with less day-1 pain (adjusted mean difference 1.58 points, 95% CI 1.14–2.01), fewer complications (adjusted risk difference 17.5 percentage points, 95% CI 9.1–25.9), and shorter median return to normal activities (7 vs. 32 days), whereas major excisional procedures had a lower adjusted risk of treatment failure by 9.6 percentage points (95% CI −17.3 to −1.9). Non-randomized allocation limits causal inference: do not present this comparison, or short-term (6–24 month) SiLaC/EPSiT series, as equivalent to long-term (5–10 year) randomized comparative evidence, and always state the follow-up duration alongside any recurrence estimate (§2.0 Guardrail 2). If phenol ablation is chosen, apply §2.0 Guardrail 1: published protocols vary in preparation (crystallized phenol vs. 80% liquid phenol), contact time, and applications — protect surrounding perianal and gluteal skin with a barrier ointment (such as petrolatum or zinc oxide paste), prevent chemical runoff toward the anal verge, express excess agent from the tract, and follow the specific product safety data sheet and institutional chemical-handling protocol.

No standalone Saudi/GCC pilonidal guideline is separately published (§2.2 regional frame); the chapter's framework draws on international society guidance and published Saudi clinical data rather than representing an official national pathway. Author-proposed regional adaptation (§2.2): base the choice between minimally invasive treatment and off-midline reconstruction on disease extent, prior procedures, wound characteristics, patient preferences, and available expertise.

• PITSTOP Cohort — Brown et al., Br J Surg 2024 (PMID 38488204)
• ASCRS 2019 Pilonidal Guideline — Johnson et al. (PMID 30640830)
• German S3 Guideline (2020/2021) & ESCP 2024 Guideline — as cited in Table 2.1

Sigmoid resection with primary colorectal anastomosis and protective diverting loop ileostomy in selected hemodynamically stable, immunocompetent WSES Stage 3 (Hinchey III purulent peritonitis) patients <85 years when bowel edges are healthy and perfused. The monograph applies a conservative clinical safety restriction: primary anastomosis is restricted to Hinchey III purulent disease with routine protective loop ileostomy diversion, while WSES Stage 4 (Hinchey IV feculent peritonitis), septic shock, severe frailty, or immunocompromise are routed to Hartmann procedure or damage-control laparotomy.

Before: Treating either Hartmann's procedure or primary anastomosis as an unconditional universal operative rule for all Hinchey III patients.

Now: Sigmoid resection with primary colorectal anastomosis and protective diverting loop ileostomy in selected hemodynamically stable, immunocompetent WSES Stage 3 (Hinchey III purulent peritonitis) patients <85 years when bowel edges are healthy and perfused. The monograph applies a conservative clinical safety restriction: primary anastomosis is restricted to Hinchey III purulent disease with routine protective loop ileostomy diversion, while WSES Stage 4 (Hinchey IV feculent peritonitis), septic shock, severe frailty, or immunocompromise are routed to Hartmann procedure or damage-control laparotomy.

Adults with perforated sigmoid diverticulitis and diffuse purulent peritonitis (WSES Stage 3 / Modified Hinchey III). Outcomes rated in the matrix: 12-month stoma-free survival (primary) and 30-day/in-hospital morbidity and mortality (secondary).

LADIES (DIVA) enrolled selected stable patients including some Hinchey IV and left ileostomy diversion optional; this monograph deliberately does not follow the trial that far (see the restriction stated in the standard above). Trial results (n = 133: 93 Hinchey III, 40 Hinchey IV): 12-month stoma-free survival 94.6% after primary anastomosis vs. 71.7% after Hartmann procedure (HR 2.79, 95% CI 1.86–4.18, p < 0.0001) — the rating is downgraded for early termination at n = 133 and open-label design.

No standalone Saudi/GCC diverticulitis guideline is separately published; Saudi tertiary centres adopt WSES 2020 guidance as an author-proposed regional adaptation (§1.2 regional frame, Tier 3).

• WSES 2020 Diverticulitis Guideline — Sartelli et al. (PMID 32381121)
• LADIES (DIVA) Trial — Lambrichts et al. (PMID 31178342)

When excisional reconstruction is required, off-midline closure (such as Karydakis advancement flap, Bascom cleft lift, or Limberg/Dufourmentel flap) is generally preferred to midline primary closure; choice among off-midline techniques or secondary healing should reflect anatomy, prior surgery, and surgeon expertise.

Before: Routine high-tension midline primary suture closure in the deep intergluteal cleft without considering off-midline closure options.

Now: When excisional reconstruction is required, off-midline closure (such as Karydakis advancement flap, Bascom cleft lift, or Limberg/Dufourmentel flap) is generally preferred to midline primary closure; choice among off-midline techniques or secondary healing should reflect anatomy, prior surgery, and surgeon expertise.

Adults undergoing excisional reconstruction for chronic pilonidal sinus disease. Outcomes rated in the matrix: wound dehiscence, healing time, and recurrence across 12- to 120-month follow-up.

Midline closures in the deep natal cleft experience higher wound dehiscence and recurrence. In Stauffer et al., RCT-only recurrence at 12, 24, and 60 months was 2.1%, 7.0%, and 21.9% for midline closure vs. 1.5%, 2.4%, and 10.2% for Karydakis/Bascom (and 0.6% at 12 mo, 1.8% at 24 mo for Limberg/Dufourmentel); in the merged RCT + non-RCT dataset (n = 89,583), Karydakis/Bascom recurrence was 0.2% (12 mo), 0.6% (24 mo), and 1.9% (60 mo). Pooled figures are study-level benchmarks rather than guaranteed individual outcomes. Wide excision with open healing by secondary intention or marsupialization is not categorically outdated — it remains an option in ASCRS 2019 and ESCP 2024 for selected complex or infected presentations when primary flap closure is unsuitable, with counselling on prolonged wound healing (median 70 days in PITSTOP; 16.5% 5-year RCT recurrence in Stauffer et al.) (§2.2 prose).

No standalone Saudi Ministry of Health or GCC-wide clinical practice guideline for sacrococcygeal pilonidal disease is identified in the sources reviewed for this chapter (§2.2 regional frame). Local evidence is the Riyadh tertiary-center retrospective cohort (Albabtain et al., n = 369): overall recurrence 22.8% (95% CI 18.6%–27.4%) at a mean of 1.8 years, with earlier recurrence after primary midline closure than after open secondary healing (1.4 vs. 2.3 years; p = 0.02) — observational associations for local audit and hypothesis generation, not proof that any single intervention prevents recurrence. Author-proposed regional adaptation (§2.2): base the choice between minimally invasive treatment and off-midline reconstruction on disease extent, prior procedures, wound characteristics, patient preferences, and available expertise.

• ASCRS 2019 Pilonidal Guideline — Johnson et al. (PMID 30640830)
• Stauffer et al. 2018 Recurrence Synthesis (PMID 29449548)
• Albabtain et al. 2021 Riyadh Tertiary Cohort (PMID 34085545)
• German S3 Guideline (2020/2021), SICCR 2021 Consensus & ESCP 2024 Guideline — as cited in Table 2.1

Perform universal tumor MMR/MSI testing on all colorectal carcinomas (dMMR Stage II tumors have favorable prognosis and do not benefit from 5-FU monotherapy). In Stage II colon cancer, postoperative plasma ctDNA at weeks 4 and 7 can inform shared decision-making alongside clinicopathological risk factors (such as pT4 stage, lymphovascular invasion, <12 nodes examined, perforation/obstruction, and tumor budding).

Before: Empiric fluoropyrimidine/oxaliplatin chemotherapy without universal mismatch repair (MMR/MSI) testing, or treating negative postoperative ctDNA as proof of zero recurrence risk.

Now: Perform universal tumor MMR/MSI testing on all colorectal carcinomas (dMMR Stage II tumors have favorable prognosis and do not benefit from 5-FU monotherapy). In Stage II colon cancer, postoperative plasma ctDNA at weeks 4 and 7 can inform shared decision-making alongside clinicopathological risk factors (such as pT4 stage, lymphovascular invasion, <12 nodes examined, perforation/obstruction, and tumor budding).

Adults with curatively resected Stage II (T3–T4, N0, M0) colon adenocarcinoma. Outcomes rated in the matrix: 2-year recurrence-free survival (primary non-inferiority endpoint) and proportion receiving adjuvant chemotherapy.

A negative ctDNA result does not establish absence of residual disease and does not override high-risk pathological features outside shared decision-making (§1.0 Guardrail 4). DYNAMIC (n = 455 randomized 2:1): ctDNA-guided management reduced adjuvant chemotherapy use from 28% to 15% (absolute reduction 13 percentage points) with 2-year recurrence-free survival 93.5% vs. 92.4% (absolute difference 1.1 percentage points, 95% CI −4.1 to 6.2; non-inferiority met). Do not conflate this with the separate dMMR immunotherapy evidence bases (NICHE-2 in colon cancer; dostarlimab in rectal cancer).

• DYNAMIC Trial — Tie et al., N Engl J Med 2022 (PMID 35657320)
• NCCN Colon Cancer Guidelines — as cited in Table 1.1