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Q&A

Labor

Poster Session 4

(927) The impact of cup size on complications in vacuum-assisted deliveries: A retrospective case-control matching analysis

Wednesday, February 14, 2024
1:00 PM – 2:30 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level

    Primary & Presenting Author(s)

  • Matan Anteby, MD

    Lis Maternity Hospital, Sourasky Medical Center, Tel Aviv, and Sackler Faculty of Medicine, Tel Aviv University
    Tel Aviv, Israel

    • Coauthor(s)

  • TP

    Tally Pinchas-Cohen, MD

    Lis Hospital for Women's Health, Tel Aviv Sourasky Medical Center
    Tel-Aviv, Israel, Israel

  • AL

    Anat Lavie, MD

    Lis Hospital for Women's Health, Tel Aviv Sourasky Medical Center
    Tel-Aviv, Israel, Israel

  • SM

    Sharon Maslovitz, MD

    Lis Hospital for Women’s Health, Tel Aviv Sourasky Medical Center, Tel Aviv University Israel
    Tel aviv, Israel, Israel

  • Liran Hiersch, MD, PhD

    MFM specialist
    Sourasky Medical Center
    Tel-Aviv, Israel, Israel

  • YY

    Yariv Yogev, MD

    Lis Hospital for Women's Health, Tel Aviv Sourasky Medical Center
    Tel Aviv, Israel, Israel

Objective:

While previous research compared different Vacuum Assisted Delivery (VAD) devices (e.g. soft vs. rigid), scarcity of data exists regarding the association between vacuum cup size and perinatal complications.

We aimed to assess the association of vacuum cup size on maternal and neonatal morbidity in vacuum-assisted deliveries (VAD).

Study Design:

A retrospective cohort study at a single university-affiliated tertiary medical center (2011-2022). The metallic Malmström device, with cup sizes of 50 or 60 mm, was used for VAD. Cup size choice was based on physician preference and with both sizes an external force pressure of 550-600 mm Hg was used. Neonatal and maternal outcomes were compared between VAD using 50 vs 60 mm cup sizes. In order to ensure comparability between the groups, we conducted a case-control matching analysis with a 1:1 ratio based on age, BMI, analgesia, nulliparity, gestational age, baby weight, episiotomy, VAD indication, fetal station, and presentation.

Results:

1. Overall, 4,703 women underwent VAD with a 50 mm Malmström cup, and 1,541 with a 60 mm cup.
2. The matching analysis included a total of 782 well-balanced cases in each group.
3. A 60mm cup was associated with a shorter mean interval from VAD initiation to delivery (4.31± 1.88 minutes vs 4.65±2.406 minutes, p=0.003) and reduced risk of cup detachment [OR 0.52 (0.31-0.89), p=0.015], with a comparable cesarean delivery rate compared to the 50mm cup (0.6% vs 0.9%); OR 0.71 [0.22-2.25], p=0.56.
4. Risk of neonatal birth trauma (brachial plexus injury, cephalohematoma, subgaleal hematoma or subdural hematoma) was higher in the 50mm group [Figure].

 5. Composite severe neonatal outcome did not differ significantly between the groups [Figure].
6. Composite maternal outcome was similar between the groups [Figure]. However, the risk of perineal tears was lower in the 60 compared to the 50 mm group [306 (39.1%) vs 369 (47.2%), OR 0.72 (0.59-0.88), p=0.001].


Conclusion:

A larger Malmström cup size (60 mm) during VAD is associated with a decreased risk of neonatal birth trauma compared to a 50 mm diameter.