Sonographic assessment of symphyseal joint distention during pregnancy and post partum with special reference to pelvic pain

Abstract

Objective. To elucidate whether there is a relationship between pregnancy-related pelvic pain and degree of symphyseal laxity. Methods. Forty-nine women were interviewed and examined and ultrasonographic measurement of symphyseal width and vertical shift was conducted at 12 and 35 weeks of pregnancy and at 5 months post partum. The patients were retrospectively classified into four groups on the basis of presence and degree of pain in late pregnancy and presence or absence of pain at follow up. Results. The prevalence of pelvic pain of any degree during pregnancy was 49%, of pronounced pain 16.3% and of severe pain 6.1%. Nineteen percent had any remaining pain at 5 months post partum. The median symphyseal width at 12 and 35 weeks of pregnancy and at 5 months post partum was 3.5 mm, 4.6 mm and 2.8 mm, the median vertical shift 0.0 mm, 0.8 and 0.9 mm respectively. Those with disabling pain during pregnancy and no pain at follow up had greater symphyseal width (6.3 mm) and vertical shift (1.8 mm) at 35 weeks of pregnancy than controls; 4.5 mm (p∞0.01) and 0.5 mm (p∞0.01) respectively. Those with disabling pain during pregnancy and persistent pain at follow up did not differ significantly from controls in symphyseal width or shift. The most severe cases were in this group. Conclusion. There is a minor pregnancy-induced physiological increase in laxity of the sym-physeal soft tissue. There is no evidence that the degree of symphyseal distention determines the severity of pelvic pain in pregnancy or after childbirth. Pelvic pain is common in pregnancy. Most authors report prevalence figures in the range of 50-60% (1). Persisting pelvic pain four months post partum was reported in 26.5% by Kogstad et al. (2) and six months post partum in 43% by O ¨ stgaard and Andersson (3). The etiology of pelvic pain during pregnancy is unknown. Enzymatic (hyaluronidase) (4, 5), hormonal (relaxin) (5, 6), metabolic (calcium) (7), mechanical (pelvic instability, sacral angle ±55 degrees) (8-10), traumatic (4) and degenerative (11) C Acta Obstet Gynecol Scand 78 (1999) mechanisms have been suggested. Five authors have reported on the relationship between pelvic pain and relaxin levels; MacLennan et al. found an association using homologous porcine radioimm-unoassay (6), whereas three out of four recent authors, using an ELISA test based on purified antibody raised against a recombinant human re-laxin found no such association (12-15). Most pregnancies are associated with an increased width and vertical shift of the pubic bones with subsequent decrease after parturition, as