Diagnosis of PPH
The majority of PPH occurs without warning; thus, consistent implementation of prevention measures, rapid PPH recognition and prompt identification and treatment of hemorrhage etiology are essential to reduce maternal mortality and morbidity. Frequent monitoring of vital signs and palpation of the uterine fundus after delivery is recommended to identify PPH development, and providers should remain cognizant of blood loss and vital signs.
Clinical track and trigger systems including defined threshold values for hemodynamic instability are used to indicate patients at impending risk of an adverse event. The California Maternity Quality Care Collaborative (CMQCC) has proposed designated values for alert and action lines (e.g., heart rate ≥110 bpm, blood pressure (BP) ≤85/45 mmHg and oxygen saturation <95%), and the UK Confidential Enquiry into Maternal and Child Health (CEMACH) developed an 'Obstetric Early Warning Chart' to alert providers to numeric and visual cues for action, used in the National Health System.[19,20] The CEMACH chart triggers a provider to urgent medical assessment when a patient demonstrates either one markedly abnormal observation or a combination of two mildly abnormal observations for the vital signs being tracked (e.g., respiratory rate, O2 saturation, temperature, heart rate, BP). Validation of this chart reported high sensitivity and reasonable specificity, but called for further refinement of low blood pressure threshold values. The Royal College of Obstetricians and Gynecologists (RCOG) recommends the use of an obstetric early-warning score system such as this for early identification of continuous bleeding. The shock index, a combined measure of pulse and systolic blood pressure (pulse/systolic bp), was found to have clinical utility for early diagnosis of hemorrhage in a recent systematic review by Pacagnella et al.; however, further research among the obstetric population is necessary. The evidence base on the effectiveness of trigger tools for reducing intensive care admissions or poor health outcomes is not well-established.
Timely recognition of PPH through accurate monitoring of blood loss at delivery and postpartum is critical in resource-poor settings, in particular, but is also useful in the developed world. The gold standard for blood loss estimation, photospectrometry or colorimetric measurement of alkaline hematin, is impractical for many clinical settings. Visual estimation is the most common method of quantifying blood loss worldwide; however, this method underestimates blood loss between 30 and 50%, with greater inaccuracy as blood loss increases. Dedicated clinical training improves the accuracy of visual blood loss estimation, and use of written and pictorial guidelines may assist labor ward staff. Devices to assist measurement such as an under-buttocks, plastic, closed-ended, calibrated blood-collection drape (Figure 1) also improve valid estimation. Clinicians may soon be able to utilize mobile phones to estimate blood loss using the camera of the phone and a built in algorithm; such a low-cost application that provides real-time blood loss monitoring via scanning is in development.
Expert Rev of Obstet Gynecol. 2013;8(6):525-537. © 2013 Expert Reviews Ltd.