Left-Sided Perforated Appendicitis in an Elderly Man with Intestinal Malrotation: A Case Report

Introduction

Left-sided acute appendicitis is exceptionally rare and typically results from congenital anomalies that displace the cecum and appendix [1,2]. In older adults, whose abdominal pain more often reflects diverticulitis or malignancy, this variant presents a formidable diagnostic dilemma because comorbidities can blunt classic inflammatory signs [3–6].

Intestinal malrotation occurs in approximately 1 in 5000 to 6000 live births, yet it remains undetected into adulthood in a small minority of patients [7,8]. In adults, the true prevalence is not well defined; most detections are incidental on cross-sectional imaging. A study of a cohort undergoing computed tomography (CT) colonography reported malrotation features in approximately 0.25% to 0.3% of examined individuals [8,9]. Specifically, type I non-rotation leaves the small bowel on the right and the colon on the left, predisposing the displaced appendix to inflame outside its usual clinical territory [8]. Although fewer than 100 adult cases of malrotation-related left-sided appendicitis have been reported, many were diagnosed only at surgery and frequently after perforation [1,2]. Our experience highlights the value of standardized CT review for an absent retromesenteric duodenum or an inverted superior mesenteric artery–superior mesenteric vein (SMA-SMV) relationship, a focused approach that may shorten time to diagnosis and improve outcomes in elderly patients.

Cross-sectional imaging is pivotal in such atypical presentations. Abdominal CT readily demonstrates malrotation by delineating key anatomic landmarks. Characteristic findings include absence of the horizontal duodenum behind the SMA – because the duodenum fails to cross to the left – and inversion of the usual SMA-SMV relationship, with the SMV situated to the left of the SMA [8,9]. In our patient, CT confirmed type I malrotation by showing a non-retromesenteric duodenum and a left-sided cecum. Moreover, CT offers high sensitivity and specificity for appendicitis (reported accuracy 90–98%) while simultaneously disclosing congenital anomalies [5,9]. As CT use has expanded, detection of malrotation in asymptomatic adults has increased, thus allowing recognition of variants that previously went unnoticed [9,10]. Therefore, in any adult who presents with unexplained left-sided symptoms suggestive of appendicitis, careful scrutiny of CT images for signs of malrotation is essential to avoid diagnostic delay.

The differential diagnosis of left lower-quadrant pain in an older man is broad. Common etiologies include sigmoid diverticulitis – the most frequent cause in Western populations – ureterolithiasis or pyelonephritis, colonic ischemia or neoplasm, and abdominal-wall or gynecologic disorders [5,11]. Less common causes include epiploic appendagitis, inflammatory bowel disease, and mesenteric vascular events. Given our patient’s hypertension and dyslipidemia, vascular causes of abdominal pain and colorectal cancer warranted particular consideration. Notably, elderly patients with appendicitis carry a higher incidence of synchronous colonic neoplasia [3]; hence, thorough colonic evaluation remains mandatory after appendectomy. In the present case, the acute left-sided peritonitis and abscess could easily have been mistaken for sigmoid diverticulitis or a perforated colon cancer, illustrating how malrotation compounds the diagnostic dilemma.

Here, we describe a 67-year-old man with hypertension, dyslipidemia, hyperuricemia, and chronic kidney disease whose perforated appendicitis manifested as left lower-quadrant pain owing to previously unrecognized type I intestinal malrotation. This case underscores the need for systematic evaluation of cross-sectional imaging when elderly patients present with atypical abdominal pain, as prompt recognition can guide minimally invasive management and reduce morbidity.

Case Report

A 67-year-old man with hypertension, dyslipidemia, hyperuricemia, and chronic kidney disease presented with 48 hours of abdominal pain that evolved from diffuse colic to sharp discomfort localized to the left flank and iliac fossa, accompanied by nausea without emesis and a documented fever of 38.5°C (101.3°F). Acetaminophen provided no relief, and bowel and urinary habits remained unchanged.

On arrival, his vital signs were stable: blood pressure 114/70 mmHg, heart rate 62 beats/min, respiratory rate 18 breaths/min, temperature 36.7°C (98.1°F), and oxygen saturation 92% on room air. Abdominal examination revealed mild distension, active bowel sounds, and focal rebound tenderness in the left lower quadrant.

Given this presentation, the differential diagnosis included acute sigmoid diverticulitis, segmental ischemic colitis, left-sided urolithiasis complicated by secondary pyelonephritis, and focal infectious colitis. These conditions were carefully evaluated and systematically excluded based on clinical findings and imaging results. For instance, sigmoid diverticulitis typically presents with lower abdominal tenderness, altered bowel habits, and characteristic colonic wall thickening on imaging, none of which were prominent in this patient. Likewise, segmental ischemic colitis was less likely because of the absence of bloody stools or cardiovascular instability. Similarly, left-sided urolithiasis and pyelonephritis were ruled out due to the absence of urinary symptoms and lack of characteristic renal or ureteral calculi on imaging. Lastly, focal infectious colitis was excluded on the basis of the clear identification of an inflamed appendix and absence of colonic wall abnormalities.

Laboratory testing demonstrated leukocytosis (leukocytes 14.88×103 cells/μL; reference, 4.0–10.0×103), neutrophilia (neutrophils 85.1%; reference, 40–75%), markedly elevated C-reactive protein level of 165.2 mg/L (reference, <5.0 mg/L), reduced estimated glomerular filtration rate of 58.1 mL4in/1.73 m2 (reference, ≥90 mL/min/1.73 m2), and elevated urea level of 44.9 mg/dL (reference, 7–23 mg/dL). Non-contrast abdominal and pelvic CT images are shown in Figure 1, axial imaging is shown in Figure 2, and an additional axial slice is shown in Figure 3.

Accordingly, an emergency laparoscopic appendectomy was performed. The laparoscopic approach was specifically selected for its minimally invasive nature, reduced postoperative morbidity, and superior visualization in the presence of atypical anatomy due to malrotation. To mitigate potential complications, such as inadvertent bowel injury from altered anatomical relationships, mirrored port placement was carefully used. During intra-abdominal inspection, malrotation was confirmed, with the cecum and a pre-ileal appendix situated in the left flank. A phlegmon involving the appendix, omentum, and terminal ileum encircled a 30-mL purulent appendiceal abscess. The appendix measured approximately 7×1 cm, was necrotic throughout, and had perforated at its mid-third, although the base remained viable. The mesoappendix and appendiceal base were divided with an endoscopic stapler, the specimen was extracted in an endoscopic bag, and the abscess cavity was thoroughly irrigated and drained, thereby preventing postoperative infectious complications. No additional intra-abdominal pathology was identified.

Gross examination and histologic findings are shown in Figure 4, confirming perforated phase IV acute appendicitis with abscess formation. Together, these findings reinforced the appropriateness of the broad-spectrum antibiotic strategy and supported the necessity for rapid surgical intervention, particularly in the context of this patient’s comorbidities and heightened susceptibility to severe infection.

Postoperatively, the patient received intravenous (IV) lactated Ringer’s solution, once-daily IV ertapenem, and scheduled analgesia with acetaminophen and dipyrone. Ertapenem was selected in accordance with the 2021 Infectious Diseases Society of America guidelines for perforated community-acquired appendicitis, as it provides broad Enterobacterales and anaerobic coverage, including protection against extended-spectrum β-lactamase-producing organisms, without unnecessary antipseudomonal activity. A total of 3 doses were administered before step-down to oral therapy. Subsequently, the patient remained nil per os for several hours before initiating a clear-liquid diet.

On postoperative day 1, the patient was hemodynamically stable, reported minimal pain, tolerated a soft intestinal diet, passed flatus, and had clean, dry laparoscopic wounds. Although mild abdominal distension persisted, bowel sounds were active.

By postoperative day 2, the patient remained afebrile and pain-free, with stable vital signs. Furthermore, the leukocyte count decreased to 7.95×103 cells/μL and C-reactive protein level to 140 mg/L. After completion of the third dose of IV ertapenem, the patient was deemed fit for discharge.

The patient was discharged with oral antibiotics, analgesics, and dietary enzymes, with instructions for outpatient follow-up and monitoring of warning signs.

Discussion

Left-sided acute appendicitis secondary to type I intestinal malrotation is exceedingly uncommon in adults, especially in elderly patients. For instance, Akbulut et al identified only 23 cases (24%) of midgut malrotation among 95 patients with left-sided appendicitis, with a mean age of approximately 29 years (range, 8–82 years), highlighting its rarity in older adults [1]. Thus, our patient, at 67 years of age, is an unusual case due to his advanced age and significant comorbidities. Moreover, unlike younger patients, elderly individuals often have atypical presentations complicated by chronic diseases, making timely diagnosis especially challenging [12].

In older patients, delayed diagnosis of malrotation-related appendicitis is common due to atypical symptoms and clinical overlap with more prevalent disorders, such as diverticulitis or ischemic colitis. Accordingly, Singla et al [12], Kharel et al [13], and Assefa et al [2] emphasize that clinicians should maintain heightened suspicion for malrotation in elderly patients presenting with atypical abdominal pain to reduce the risk of complications, including perforation and peritonitis. Indeed, in our patient, delayed recognition due to initial nonspecific symptoms underscored the importance of considering congenital anomalies, even in elderly populations.

Given these risks, CT is the study of choice in adults with suspected malrotation because it can both confirm appendicitis and delineate variant anatomy in a single examination. Key signs include failure of the third (retromesenteric) portion of the duodenum to cross the midline, inversion of the usual SMA–SMV relationship (with the SMV to the left of the SMA), right-sided jejunum, and a left-sided colon [8,14–16]. In a CT colonography cohort of more than 11 000 adults, malrotation features were present in approximately 0.2% to 0.3%, most commonly manifested by abnormal SMA-SMV orientation and a left-sided colon [15]. Contemporary series further refine these clues: the “absent retromesenteric duodenum” has been validated as a reliable adult marker [8], and a 332-case analysis reported that only 25% had complete non-rotation (type I) and merely 4.5% retained the textbook right-small-bowel/left-colon configuration [16]. In our patient, CT demonstrated a non-rotated bowel with an inverted SMA-SMV relationship, which directly guided timely laparoscopic management.

Adult cases of left-sided appendicitis due to malrotation – without concomitant situs inversus – are scarce. Previous reports, such as those involving a 23-year-old man and a 77-year-old woman, demonstrate that acute appendicitis can constitute the first clinical manifestation of an unrecognized malrotation [1,2]. Furthermore, unlike most left-sided appendicitis cases linked to situs inversus, our patient’s only anomaly was type I malrotation. This finding reinforces the need to consider malrotation in the differential diagnosis even when classic stigmata of situs inversus, such as dextrocardia, are absent. In summary, this case underscores that intestinal malrotation, although rare in adults, must be identified preoperatively through imaging in order to diagnose left-sided appendicitis accurately and to plan definitive surgical management.

Once left-sided appendicitis due to malrotation is diagnosed, laparoscopy offers significant advantages, including minimally invasive exploration and rapid recovery. Therefore, we recommend mirrored port placement to recreate the standard spatial relationship for effective management of the abnormal anatomy, reducing surgical complications and enhancing patient outcomes. AlKeileh et al, for instance, successfully treated a 12-year-old patient with laparoscopic appendectomy and emphasized that laparoscopy is “minimally invasive with fewer complications” [17]. Trocar placement can be modified by mirroring the conventional configuration: indeed, one report describes the use of an infraumbilical camera port, a suprapubic port, and a working trocar in the contralateral iliac fossa (the patient’s right side) to access the left-sided appendix [18]. This arrangement effectively recreates the usual spatial relationship to the inflamed appendix. Moreover, laparoscopy facilitates division of any Ladd bands encountered; however, our patient required appendectomy alone. Multiple authors agree that a laparoscopic approach is safe for left-sided appendicitis [17] and avoids the morbidity associated with a larger incision. Although laparoscopic and open techniques have been reported [12], minimally invasive surgery is generally preferred when expertise permits.

Our case adds valuable insights to the limited literature on left-sided appendicitis secondary to type I intestinal malrotation in elderly adults. Given the atypical presentation and risk of diagnostic delays in this demographic, clinicians should therefore adopt structured imaging protocols emphasizing characteristic CT findings. Moreover, early recognition combined with minimally invasive laparoscopic appendectomy using mirrored port placement is an optimal diagnostic and therapeutic strategy, reducing morbidity and improving outcomes in similar cases.

Conclusions

Left-sided perforated appendicitis secondary to type I intestinal malrotation may first manifest in advanced age, masquerading as more common left lower-quadrant disorders and thereby heightening the risk of harmful diagnostic delay. Consequently, systematic scrutiny of cross-sectional imaging for malrotation hallmarks – absence of a retromesenteric duodenum, inversion of the superior mesenteric vessels, and an ectopic cecum – should be mandatory whenever unexplained left-sided appendicitis is suspected, particularly in older patients with comorbidities. Accordingly, clinicians should maintain a high index of suspicion for intestinal malrotation in elderly patients presenting with left lower-quadrant pain to prevent delayed diagnosis and avoid unnecessary resections. Early recognition, in turn, permits a tailored laparoscopic appendectomy using mirrored port placement, minimizes morbidity associated with open exploration, and avoids extensive colonic resections caused by misdiagnosis. Finally, future investigations should quantify the prevalence of asymptomatic malrotation in the elderly and evaluate standardized CT protocols that expedite detection of this rare yet clinically significant anatomical variant.