Researchers have developed a new imaging tool, called electromyometrial imaging (EMMI), to create real-time, three-dimensional images and maps of contractions during labour that could help with managing labour.
The non-invasive imaging technique generates new types of images and metrics that can help quantify contraction patterns, providing foundational knowledge to improve labour management, particularly for preterm birth, they said in a study.
The study led by Washington University and University of Texas, US, is published in the journal Nature Communications.
"EMMI has the potential to answer critical questions about uterine contractions and will help us better understand what occurs during pregnancy and labour," said Diana W. Bianchi, Director of National Institute of Child Health and Human Development (NICHD), US.
"With additional research, the tool may potentially predict who is at risk to deliver prematurely or whose labour pattern will eventually result in the need for a cesarean section delivery.
"This will also help care providers evaluate whether a treatment or intervention is working," said Bianchi.
The team of researchers initially developed EMMI using a sheep model and reported their findings in the journal Science Translational Medicine.
In the new study, the team tailored EMMI for human clinical use and tested it among a group of 10 women with healthy pregnancies.
Current clinical methods to measure contractions, i.e., tocodynamometry and an intrauterine pressure catheter, can only provide limited details, such as contraction duration and intensity, while also being invasive.
According to the study, EMMI integrated two types of non-invasive scans - a fast anatomical MRI to obtain an image of the uterus, which can be taken during early term pregnancy, or 37 weeks gestation, and a multi-channel surface scanning electromyogram that uses sensors placed along the belly to measure contractions during labour.
These data are then combined and processed into three-dimensional uterine maps, with warm colours denoting areas of the uterus that are activated earlier in a contraction, cool colours indicating areas that are activated later and gray areas showing inactive regions, the study said.
A sequence of maps is generated over time, creating a visual timelapse that shows where contractions start, how they spread and/or synchronize, and potential patterns that are associated with a typical pregnancy versus one with complications, the study said.
EMMI maps were also used to develop metrics to describe uterine contractions. The maximal activation ratio, for example, measures the total surface area of the uterus that becomes electrically active during an individual contraction. The activation curve slope measures the rate of uterine electrical activation. The fundal early activation ratio helps quantify the region that generates contractions to dilate the cervix.
Results from the pilot study also bring clarity on a longstanding question on how contractions begin - EMMI data suggest there is no fixed, pacemaker-like region in the uterus that initiates labour.
The study team observed varied patterns of contractions and metrics among the 10 study participants, with some similarities between women who had never given birth and those who had.
However, more research is needed to confirm and expand upon these observations, the team said.
The authors noted that an EMMI contraction atlas generated from healthy pregnancies can serve as a resource to understand and diagnose preterm labour and possibly identify patients who would benefit from an induction versus those who may need a cesarean section.