Rheumatology 2001; 40: 1191-1192
© 2001 British Society for Rheumatology
Letters to the Editor |
Post-partum septic sacroiliitis
University College London Hospital NHS Trust, Centre for Rheumatology, Tottenham Street, London W1T 4NJ, UK
SIR, A 37-yr-old woman had an uncomplicated vaginal delivery of her third child in August 1999. Labour was induced at 41 weeks' gestation. The placenta was normal on visual inspection. She was discharged feeling well. Six days post-partum she felt unwell and hot with pain and swelling in her right ankle and in the area of the left hip. She had no history of trauma and there was no significant medical or family history.
On admission she was pyrexial at 38°C, tachycardic at 130 b.p.m. with a blood pressure of 100/50. The abdomen was enlarged and tender. Her right ankle was swollen, hot and tender. There was apparent tenderness of the left hip. This was later found to originate from the left sacroiliac joint.
Investigations revealed a normal haemoglobin, total white cell count, urea and electrolytes and international normalized ratio (INR). Abnormal investigations (with normal ranges in parentheses) included platelet count 53x109/l (150–400x199/l), bilirubin 43 µmol (3–17 mol/l), alkaline phosphatase 142 U/l (32–104 U/l), albumin 24 g/l (35–50 g/l), C-reactive protein (CRP) 506 mg/l (0–5 mg/l), glucose 2.5 mmol/l (3.3–5.6 mmol/l). Chest radiography showed fluid in the right horizontal fissure. Vaginal swabs and blood cultures grew group A Streptococcus pyogenes. Microscopy of aspirated ankle fluid showed pus cells but no organisms. She was HLA B-27 negative.
A diagnosis of post-partum streptococcal septicaemia was made and she was commenced on intravenous benzylpenicillin and clindamycin. Her condition deteriorated rapidly with haemoglobin and platelets dropping to 8.2 g/dl and 41x109/l, respectively. At laparotomy, 2 l of ascitic fluid was drained. A subtotal hysterectomy and partial right oophorectomy were performed. Post-operatively she remained pyrexial and continued to complain of pain around her left hip and right ankle. Her pelvic radiograph showed periarticular sclerosis of the left sacroiliac joint with joint destruction. An isotope bone scan showed increased uptake in the right ankle and left sacroiliac joint. Magnetic resonance imaging (MRI) scans revealed left-sided sacroiliitis with a small abscess at the upper joint margin and a further 3 cm collection at the lower joint margin extending into the iliac notch (Fig. 1
). There was no significant bone marrow oedema. The right ankle showed gross synovial thickening around the ankle joint and around the tendons of tibialis posterior, flexor digitorum longus and flexor hallucis longus. No focal osteomyelitis was seen.
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A computed tomography (CT)-guided aspiration of her abscess was performed which yielded 4 ml of pus. The patient reported immediate relief of her symptoms. She was discharged non-weight bearing and afebrile. The total length of antibiotic treatment was 3 months. Since discharge she has become totally pain free but is left with some loss of right ankle dorsiflexion.
Pyogenic sacroiliitis is an uncommon condition with a reported incidence rate varying from 1.5 to 10% of all pyogenic joint infections [1]. It is associated with trauma to the pelvis, intravenous drug abuse and gynaecological infections. Pregnancy is a rare association. Early diagnosis allows the best chance of preventing complications. Puerperal sepsis due to group A streptococci used to be a major cause of death. Recent statistics have shown 10 cases of death after vaginal delivery, of which five were due to group A streptococcal infection [2]. During pregnancy, the pelvic joints and ligaments relax and pelvic movements increase. It has been hypothesized that puerperal sacroiliitis is related to microscopic areas of injury on the joint surfaces produced by the changes during pregnancy [3].
In a series of 47 cases of pyogenic sacroiliitis [4], 16 patients had puerperal infections and two had gynaecological infections. Pyelonephritis was found to be the source of infection in one case [5]. In a review of 166 patients [6], Staphylococcus aureus occurred in 44% of cases and Streptococcus pyogenes in only three cases.
Pyogenic sacroiliitis is usually unilateral, but it can occur bilaterally [1]. It usually presents with pain in the buttock region. The erythrocyte sedimentation rate (ESR) is nearly always elevated, although the total white cell count can be normal. Plain radiography of the sacroiliac joints may be normal in early disease, unlike our case where changes were evident. There may be blurring of the joint margins, a widened joint space or periarticular erosions. Radioisotope bone scans in pyogenic sacroiliitis have a higher specificity and sensitivity than in inflammatory disease, and can be positive 48–72 h after the onset of symptoms [7]. CT can show changes when a bone scan is negative, and is the best technique if guided biopsies need to be performed. MRI scanning gives no radiation exposure and good visualization of cartilage, bone and soft tissues. In a study of 17 subjects with sacroiliitis, two of whom had sepsis, MRI was shown to be superior to CT in the detection of infectious and inflammatory sacroiliitis [8].
Findings supporting sepsis rather than inflammation include unilateral disease and marked soft tissue and marrow oedema. There is no consensus on the duration of antibiotic therapy, but initial treatment should be given intravenously to maximize the bactericidal effect. Oral therapy should only be instituted once the patient's clinical condition has stabilized and compliance is ensured. Inflammatory markers such as the ESR or CRP can be used to assess response to treatment. If all cultures are negative or the patient is not improving, a CT-guided biopsy of the joint may be required, especially if an abscess is present. An open biopsy may be needed if other procedures have failed.
With prompt treatment, long-term complications are few. A diagnosis of pyogenic sacroiliitis should always be considered in the ‘at risk’ groups of pregnant women, intravenous drug abusers, and those on immunosuppressant drugs who present with acute or subacute low back/hip pain and difficulty weight bearing.
Notes
References
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- Moore KL, Dalley AF. Clinically oriented anatomy. Baltimore, MD: Lippincott, Williams & Wilkins, 1999:340–1.
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Delbarre F, Rondier J, Delrieu F. Pyogenic infection of the sacroiliac joint. J Bone Joint Surg Am1975;57:819–25.
[Abstract/Free Full Text] - Egerman RS, Mabie WC, Eifrid M, Whitnack E, Sibai B. Sacroiliitis associated with pyelonephritis in pregnancy. Obst Gynaecol1995;85:834–5.
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[Abstract/Free Full Text]
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