Risk factors for uterine atony/postpartum hemorrhage requiring treatment after vaginal delivery

Abstract

Objective To identify risk factors for uterine atony or hemorrhage. Study Design Secondary analysis of a 3-arm double-blind randomized trial of different dose-regimens of oxytocin to prevent uterine atony after vaginal delivery. The primary outcome was uterine atony or hemorrhage requiring treatment. Twenty-one potential risk factors were evaluated. Logistic regression was used to identify independent risk factors using 2 complementary pre-defined model selection strategies. Results Among 1798 women randomized to 10, 40 or 80U prophylactic oxytocin after vaginal delivery, treated uterine atony occurred in 7%. Hispanic (OR 2.1; 95% CI 1.3–3.4) and non-Hispanic whites (OR 1.6; 95% CI 1.0–2.5), preeclampsia (OR 3.2; 95% CI 2.0–4.9) and chorioamnionitis (OR 2.8; 95% CI 1.6–5.0) were consistent independent risk factors. Other risk factors based on the specified selection strategies were obesity, induction/augmentation of labor, twins, hydramnios, anemia, and arrest of descent. Amnioinfusion appeared to be protective against uterine atony (OR 0.53; 95% CI 0.29–0.98). Conclusion Independent risk factors for uterine atony requiring treatment include Hispanic and non-Hispanic white ethnicity, preeclampsia and chorioamnionitis.

Research of the assessable method of postpartum hemorrhage

“…The primary goal of this study was to determine parturients at high risk of PPH in order to reduce mortality. The risk factors are shown in Table 1, and experimental results are consistent with the reported literature [13][14][15][16]. Blood clotting function tests include fibrinogen (FIB), plasma prothrombin time detection (PPTD) and so on [17][18][19][20].…”

How I treat postpartum hemorrhage

“…Uterine atony ("Tone") is the most common cause; failure of the myometrium to contract allows continued bleeding from the spiral arteries. Risk factors for uterine atony are well established, 69,70 however, they only have moderate positive predictive value for PPH and hence limited clinical utility. Most cases of uterine hemorrhage are not predictable but for those with known preexisting factors, such as placenta previa or previous PPH, we discuss and agree upon a delivery plan in advance.…”

Prospective study of association of uterine atonicity and serum calcium levels

“…Nifedipine, Mgso and calcium channel blockers used during delivery were reported tobe associated with uterine atony, suggesting that low serum calcium may be associated with uterine atony. 4,13 …”

“…The oxytocic drugs increase the uterine tone by increasing intracellular calcium. [3][4][5] Therefore optimum levels of calcium are very important for the effective uterine contractions. Calcium exerts its effect by activating the muscle proteins and causing effective uterine contraction.…”