Chronic Pelvic Pain Reveals Sacral Osteomyelitis Three Years after Abdominal Hysterectomy

Case Report

A 46-year-old woman presented with an 8-month history of abdominopelvic pain recently intensified when she was in the sitting position, and with left sacroiliac pain. She denied experiencing fever, night sweats, or weight loss. Her medical history revealed an uncomplicated total abdominal hysterectomy for a leiomyomatous uterus three years previously. No evidence of gastrointestinal or gynecologic disease was present. An abdominal ultrasound scan followed by an abdominopelvic computed tomography (CT) scan was unremarkable except for S2 sacral osteolysis with intracanalar extension (Fig. 1). A malignant tumor was suspected, and the patient was referred to our institution for further evaluation and treatment.

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FIG. 1.

Pelvic axial computed tomography scan showing osteolytic process involving second sacral segment with intracanalar extension mimicking malignant tumor.

Her body temperature was normal. Neurologic examination did not show any focal deficits. Gynecologic, urinary, and rectal examination did not yield positive findings. Laboratory evaluation was normal except for mild inflammation (C-reactive protein [CRP] 9.1 mg/L; and erythrocyte sedimentation rate [ESR] 20 mm/h]. Bone scintigraphy demonstrated non-specific increased activity in the sacrum and left sacroiliac junction. A magnetic resonance imaging (MRI) scan revealed a large sacral fluid collection from S2 to S4, extending into the epidural space and compressing the distal thecal sac. This cystic process manifested as low signal intensity on T₁-weighted images and high signal intensity on T₂-weighted images with ring-like gadolinium enhancement and presacral extension (Fig. 2). A posterior CT-guided biopsy and aspiration drained about 40 mL of thick green fluid. Histologic analysis showed inflammatory granulations without any malignant tumor. Abscess culture grew Staphylococcus epidermidis, S. hominis, and Streptococcus sanguis. Tests for mycobacteria and mycosis were negative.

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FIG. 2.

Sacral spinal magnetic resonance imaging. Sagittal T₁-weighted image with gadolinium (A) and sagittal T₂-weighted image (B) reveal large fluid collection from S2 to S4 extending into epidural space and compressing distal thecal sac. This cystic process manifested as low signal intensity on T₁-weighted images and high signal intensity on T₂-weighted images with ring-like gadolinium enhancement and presacral extension.

The patient received a 10-day course of intramuscular gentamicin (160 mg/day). Ciprofloxacin was given intravenously for four weeks (600 mg/day), then orally for eight weeks (1 g/day). Laboratory tests for inflammation were normal three months after treatment initiation. At the same time, the patient's symptoms had resolved completely. She remained symptom-free for 12 months of follow up.

Discussion

Sacral osteomyelitis is a rare infection even in neurosurgical and orthopedic practices [11–14,16,17]. This infection is rarely described postoperatively, but it can have serious local and systemic sequelae [7,8,18]. In gynecology, the most common procedure complicated by SOM is abdominal sacral colpopexy (five cases reported) [4,7–9]. In fact, the sacrum alone is rarely infected; it is more precisely described as lumbosacral spondylodiskitis [11,13–16]. As proposed by Taylor et al., this complication may result in a fistulous tract from the vaginal apex to the sacrum and, eventually, a sacral abscess impinging on the spinal column with diskitis and osteomyelitis [7].

On the other hand, the most common infections associated with total abdominal hysterectomy are nosocomial urinary tract infection, wound infection, and pelvic abscess [1,2,6,10]. Ahmed and Wasti reported only a 0.4% incidence of postoperative pelvic abscess in a series of 827 consecutive abdominal hysterectomies. No SOM was identified [1].

The occurrence of SOM after pelvic surgery often is a late manifestation of disseminated pathogens [7,8,18]. The insidious progression of infection, the permissive surrounding anatomic environment, and the non-specificity of the symptoms may lead to a diagnostic delay, as occurred in our patient [16,18]. This case report demonstrates the need to consider SOM in the differential diagnosis for patients with chronic pelvic or abdominal pain, regardless of a history of hysterectomy. Another unusual element of this case was the absence of neurologic deficit despite the extent of disease.

Plain radiography frequently fails to reveal the true extent of osteolysis. Axial CT scan or, preferably, MRI is necessary for full evaluation of the anatomical characteristic of the osteolysis and its extension into the surrounding structures [14,17,19]. Sacral osteomyelitis can mimic osteolytic malignant tumor, leading to mutilating surgical excision [11,17,19]. Sacral transpedicular percutaneous biopsy with aspiration is a safer minimally invasive option; it may confirm the diagnosis and limit the extent of surgical intervention [20,21]. Antibiotic therapy should be administered for at least 12 weeks and until the CRP and ESR are normalized [15].

Conclusions

Sacral osteomyelitis has not been reported previously after transabdominal hysterectomy. Such infection usually presents late in the postoperative period, and early diagnosis was made difficult by the absence of neurologic findings. Postoperative sacral infection should be considered in patients with histories of hysterectomy or other pelvic surgery to avoid unnecessary examinations and treatments. A CT-guided percutaneous aspiration is a safe minimally invasive option; it may confirm the diagnosis and limit the extent of surgical intervention.

Author Disclosure Statement

No competing financial interests exist for any of the authors.