Pishnamaz et al. Journal of Medical Case Reports 2012, 6:98 http://www.jmedicalcasereports.com/content/6/1/98 ultrasonography. An MRI of her spine and pelvis was obtained. It did not show an ischemic or inflammatory process but did reveal a non-displaced fracture of the right lateral mass of her sacrum with surrounding osseous edema (Figure 1). Our patient continued to have persistent severe pain despite oral analgesics and immobilization. A Patrick’s test was positive and our patient complained of a mas- sive pain in her lower back which increased on direct pressure to the iliosacral joint. She was therefore given epidural anesthesia. She was started on a regimen of ropivacaine 0.2% and sufentanil 0.5 μg/mL. On the sec- ond day, the sufentanil was discontinued and she con- tinued to receive ropivacaine only. Thereafter, she experienced significant pain relief. Under regular fetal cardiotocographic monitoring, our patient was then able to mobilize under physiotherapeutic guidance. The remaining course of her pregnancy was uneventful. A qualitative bone density measurement (osteosonometry) performed by her gynecologist one week after delivery showed no signs of pregnancy-related osteoporosis. At the end of her pregnancy, our patient was comple- tely free from pain. She did not opt for a Cesarean sec- tion, as per our recommendation, and delivered a healthy girl weighing 2,950 g by normal spontaneous vaginal delivery at term. In the postpartum period, she could walk with oral analgesics and experienced a clini- cally uneventful healing of the sacral stress fracture. Discussion The etiology of intrapartum or postpartum sacral stress fractures has thus far not been determined. To date, 29 cases of sacral stress fractures in athletes have been described in the literature [2]. To the best of our knowl- edge, nine cases of postpartum stress fractures have been described. Of these, only six cases have reported the patient’s bone density: five presented with normal and one with decreased bone density [11,12]. The incidence Figure 1 Coronal and axial short inversion-time inversion- recovery sequence magnetic resonance imaging of the sacrum shows the fracture line of the right lateral mass surrounded by an area of edema. Page 2 of 3 of pregnancy-related osteoporosis is approximately 0.4 cases per 100,000 women. Sacral stress fractures present universally with pain localized to the lower back, sacroi- liac region, buttocks or groin. Radicular pain is common and described in a number of cases [2,6]. A positive Patrick’s test or a tender sacroiliac joint is typically found on clinical examination. There are several other tests to localize sacroiliac joint pain that are also useful in the examination of sacral stress fracture (Table 1, [13]). Imaging is paramount in securing the diagnosis. Con- cerns regarding radiation exposure to the developing fetus limit the imaging options. Plain radiographs expose the unborn child, and are only utilized for ruling out other sources of pain. Shah and Stewart [2] reviewed a series of 27 sacral stress fractures and found 25 cases with normal radiographs. MRI is the modality of choice during pregnancy because of its lack of radiation emissions. As in our patient, all cases described in the literature involved a vertical fracture line with surrounding edema on the MRI scans. If neces- sary, after delivery, bone scintigraphy or bone scans with higher sensitivity than MRI can be utilized [2]. Bone density measurements should be performed to rule out pregnancy-related osteoporosis. Because of the high radiation load, the investigation should occur only after the pregnancy has ended. For assessment of the bone density during pregnancy, osteo- sonometry can be considered, but its use is controversial and not evidence-based. Pregnancy-related osteoporosis most often occurs in the third trimester [14,15], and if the bone mineral den- sity does not normalize within five to ten years of the delivery, then the osteoporosis is likely to be permanent [14]. Along with sacral fractures, vertebral compression fractures as well as osteoporosis of the proximal femur are associated with pregnancy. Therefore these areas Table 1 Specific pain tests for the iliosacral-region from Dreyfuss et al. [13] Sensitivity (%) Specificity (%) Test Pressure to sacral sulcus Pain at iliosacral joint Pain radiation to the buttock Pain at posterior iliac spine Bouncing Gaenslen’s test Patrick’s test Pressure to the center of sacrum Thigh thrust Pain radiation to the knee Pain in sitting position and lifting up the pelvis 95 85 80 76 75 71 69 53 36 19 3 9 8 14 47 35 26 16 29 50 63 90