OB Early Warning Criteria

Monitoring, also known as clinical surveillance, is ongoing patient assessments that identify problems and trigger responses. A warning system is a process that defines observation criteria and sets a limit to trigger a response. Although non-obstetric warning systems have existed for over twenty years, there has not been a system for obstetric women until 2011, when the United Kingdom began to introduce a formal maternal early warning system (Nair et al., 2020).

Maternal morbidity and mortality are still on the rise in the United States. Severe maternal morbidity has risen by over 144% in the United States from 1987 to 2019 (Centers for Disease Control and Prevention [CDC], 2023). There are some potential reasons for this increase including (National Institute of Health [NIH], 2018):

• Increases in maternal age
• Pre-pregnancy obesity
• Preexisting chronic medical conditions
• Cesarean delivery

Additional conditions including hemorrhage, hypertension, infection, and venous thrombosis (VTE) with delays in recognition, diagnosis, and treatment can cause many preventable maternal deaths as well (Xu et al., 2022).

In 2011, The Centre for Maternal and Child Enquiries recommended that the Maternal Early Warning System (MEWS) started to be introduced into maternity units in the United Kingdom. Since then, there are variations in the MEWS that are used across the world (Nair et al., 2020). The National Partnership for Maternal Safety devised maternal early warning criteria (MEWC) for use in maternal early warning systems (Arnolds et al., 2019). Maternal early warning criteria can prevent maternal morbidity and mortality.

Maternal mortality reviews have shown that in women who died, a disproportionate number demonstrated abnormal vital signs, suggesting that a single-parameter system should maximize specificity for patients developing a critical illness (Friedman et al., 2018; Mhyre et al., 2014). The MEWS was created to account for normal physiologic changes that occur in pregnancy. There are many variations of the MEWS, but common parameters include:

• Heart rate
• Respiratory rate
• Blood pressure
• Level of consciousness
• Oxygen saturation

Other important parameters may include:

• Level of pain
• Lochia
• Urine output

Different designs of MEWS have shown different results, leading to the need for more additional research. Please reference the following table for the specific parameters of the Maternal Early Warning Criteria.

(Friedman et al., 2018)

These triggers cannot address every potential clinical scenario that could be faced by an obstetric clinician and should not replace clinical judgment. As a core safety principle, the bedside nurse should always feel comfortable with escalating concerns at any point (Friedman et al., 2018).

All patients who meet any of The Maternal Early Warning Criteria should receive prompt bedside evaluation by a provider with the ability to activate resources to initiate emergency diagnostic and therapeutic interventions as needed (Friedman et al., 2018).

It is important to note that one abnormal measure could have been inaccurate; therefore, it should be repeated. If the patient's provider is unavailable for a prompt evaluation, a covering provider should evaluate the patient. If a woman meets the criteria and the reason cannot be determined, a maternal-fetal medicine consult, a hospital intensivist consult, or a rapid response team action should be initiated. Some electronic medical records (EMRs) can be programmed to alert the RN and page appropriate resources (such as the attending physician) automatically when the patient meets the criteria (Friedman et al., 2018).

The most significant barrier to implementing an early warning criteria system is both a physician and administration buy-in. Providers may not want to be bothered, especially when unavailable. Therefore, it is crucial to have an in-house provider to cover these circumstances. However, many providers are reluctant to respond to and treat other providers' patients. Nurses making the call to the provider may have difficulty calling a provider who will not respond appropriately. It is vital for hospital administration to support an early warning criteria policy and ensure that providers follow it. Nurses may improve the use of the criteria if they receive praise or acknowledgment for using the criteria appropriately (Friedman et al., 2018).

The Council on Patient Safety in Women's Healthcare, a subcommittee of the American College of Obstetrics and Gynecology (ACOG) and the Association of Women's Health, Obstetric, and Neonatal Nursing (AWHONN) both support the use of maternal early warning criteria.

Each hospital should have a policy that includes (AIM, 2022; Arnolds et al., 2019):

• Criteria to trigger the early warning system
• Whom to notify
• How to notify them
• How rapidly to expect a response
• When and how to activate the clinical chain of command in order to ensure an appropriate response is taken

Sarah is a 42-year-old woman who delivered her first baby via c-section 3 hours ago. She had moderate to heavy bleeding during her recovery. Her estimated blood loss measured 1200 mL. Her vital signs have been stable.

Sarah is transferred to the mother-baby unit at 11:00 pm. She begins to complain of severe abdominal pain. She is given hydromorphone (Dilaudid) for her pain that she rates as a 9 out of 10 on the pain scale. Her bleeding is moderate. Her assessment includes:

• BP 128/84
• HR 140
• Respirations 18
• Temperature 98.6
• Oxygen saturation is 98% on room air
• Urine output is adequate

The RN assumes the elevated HR is due to her pain. The RN returns in 1 hour to check on this patient and finds her lethargic with a BP of 90/60, HR 150, and an oxygen saturation of 94%. The RN calls a rapid response. The patient ends up in the operating room with a massive hemorrhage requiring a massive transfusion and subsequent transfer to the intensive care unit.

Let's reflect on this case:

• Were the RN's actions appropriate?
• Should the early warning criteria have been activated?
• Could the massive transfusion have been prevented?

At 11:00 pm, the patient's HR met early warning criteria. Her HR should have been rechecked and the provider called. The RN's actions were not appropriate. Her HR could have been elevated due to pain, but the woman had already had a hemorrhage, and her bleeding was still moderate. A massive transfusion may have been prevented if the patient had been treated with blood products sooner, but it is impossible to say it was preventable. The woman could have and should have received care sooner.

Maternal early warning criteria can prevent maternal morbidity and mortality. There are studies to support the effectiveness of these criteria. There are cases of complications such as preeclampsia that may not be preventable, but prompt treatment may prevent maternal morbidity or mortality. All nurses should know these criteria and have a process to activate a response.

• Alliance for Innovation on Maternal Health. (AIM). (2022). Severe hypertension in pregnancy. Alliance for Innovation on Maternal Health (AIM). Visit Source.
• Arnolds, D., Smith, A., Banayan, J., Holt, R., & Scavone, B. (2019). National partnership for maternal safety recommended maternal early warning criteria are associated with maternal morbidity. Anesthesia & Analgesia,129(6), 1621-1626. Visit Source.
• Centers for Disease Control and Prevention. (CDC). (2023). Pregnancy mortality surveillance system. Retrieved April 1st, 2024. Visit Source.
• Friedman, A., Campbell, M., Kline, C., Wiesner, S., DAlton, M., & Shields, L. (2018). Implementing obstetric early warning systems. American Journal of Perinatology Reports, 8(2), e79-e84. Visit Source.
• Mhyre, J., DOria, R., Hameed, A., Lappen, J., Holley, S., Hunter, S., Jones, R., King, J., & DAlton, M. (2014). The Maternal Early Warning Criteria: A proposal from the National Partnership for Maternal Safety.Journal of Obstetric, Gynecologic & Neonatal Nursing. 2014;43(6):771-779. Visit Source.
• Nair, S., Dockrell, L., & Colgain, S. (2018). Maternal early warning scores (MEWS). World Federation of Societies of Anesthesiologists (WFSA) Resource Library. Visit Source.
• National Institute of Health. (NIH). (2018). What are some factors that make a pregnancy high risk? Eunice Kennedy Shriver National Institute of Child Health and Human Development, U.S. Department of Health and Human Services. Visit Source.
• Xu, Y., Zhu, S., Song, H., Lian, X., Zeng, M., He, J., Shu, L., Xue, X., & Xiao, F. (2022). A new modified obstetric early warning score for prognostication of severe maternal morbidity. BMC Pregnancy Childbirth, 22, 901. Visit Source.