Intra-abdominal pressure in term pregnancy and postpartum.

Abstract

Introduction Data on intra-abdominal pressure (IAP) measurement in pregnant women are scarce. It has been suggested recently that elevated IAP might play a role in some gestational complications, such as (pre)eclampsia (1,2). Aim To measure intra-bladder pressure, using the Foley Manometer Low Volume technique (FMLV, Holtech Medical, Charlottenlund, Denmark), as estimate for IAP in women with uncomplicated term pregnancies, before and after caesarean section (CS) and in relation to maternal and fetal characteristics. To evaluate the effect of different zero reference levels on IAP-values. To evaluate the reproducibility of FMLV during pregnancy.

Material and methods IAP was measured 3 times per session according to a standard protocol in 24 term pregnant women before and after CS, as well as in 27 other women 15 minutes after and 1 day after a laparoscopic assisted vaginal hysterectomy (LAVH). Maternal weight and BMI and fetal position were recorded. The midaxillary line was used as zero reference (IAPMAL) in all patients, and in a fraction of 26 patients the symphysis pubis (IAPSP) was used as an alternative zero reference. The intra-session intra-class correlation (ICC) and Pearson’s correlation of IAP with maternal and fetal characteristics were calculated using SPSS 20.0. Results Mean IAPMAL was significantly higher before CS than after CS (13.7±2.7mmHg versus 9.7±2.9mmHg, p=0.012) and IAP after CS was not different from IAP in the LAVH-group (figure 1). The patient’s weight and BMI before CS correlated with postoperative IAPMAL (r=0.50, p=0.01 and r=0.43, p=0.03 respectively), but not with IAPMAL before CS. A negative correlation between IAPSP and breech presentation was observed (r=-0.54, p=0.04). Overall mean IAPSP was significantly lower than IAPMAL (p<0.001), but IAPSP measurement was technically more difficult than IAPMAL. Overall ICC for IAPMAL and IAPSP was ≥ 0.73 and ≥ 0.83 respectively. ICC before CS was lower than after CS (0.73 versus 0.87 for IAPMAL). Discussion There is a significant decrease in gestational IAP to non-pregnant values after delivery. The observed correlation between the fetal intra-uterine positioning and the maternal IAP suggests that there might be a direct pressure effect of the gravid uterus and/or the fetal position on the bladder, which subsequently might influence the measured IAP. According to our results of FMLV measurements using SP as zero reference level, higher ICC are obtained than with IAPMAL at the cost of a technically more difficult method. IAP measurement in pregnant women using the FMLV is highly reproducible as one single measurement is already reliable. Conclusion It can be stated that pregnancy is associated with high values of IAP, which depend on pre-gestational BMI and fetal position. Using alternative zero reference points in the FMLV technique is both beneficial and disadvantageous at the same time. One single IBP measurement is sufficient to reliably define IAP in term pregnant women. Further studies are needed to assess the relevance of increased IAP to normal and pathological course of pregnancy.