Impacted Fetal Head

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Reading: From SASCOG’s Pearls of Exxcellence - Cesarean Delivery with Deeply Impacted Fetal Head 

Imagine the scenario: 

You are called to do an urgent C-section as an intern for a patient with arrest of second stage of labor. Per sign out, the patient has been pushing for almost three hours and the fetal station has never made it below +1. There is significant caput. What are some of the things you should be thinking about to hopefully make this C-section easier? 

How do I identify an impacted fetal head? 

  • What it is: 

    • There have been various definitions proposed - basically, most of the definitions center on having a fetal head becoming deeply engaged within the maternal pelvis resulting in difficult extraction 

    • Complicates 1.5% of cesarean births and up to 25% of emergent cesarean births 

  • Risk factors 

    • Fetal malposition - ie. occiput posterior and occiput transverse positions

      • OP positioning leads to a larger occipitofrontal diameter (11.5cm) passing through the pelvic outlet compared to OA (9.5 cm) 

      • See more on this in our malposition and malpresentation episode!

    • Prolonged second stage 

    • Failed operative vaginal delivery 

    • Basically, anything that can wedge the head into the pelvis 

  • Identifying an impacted fetal head 

    • There is not a 100% way of identifying that a fetal head will be impacted before you actually do the C-section and you reach down into the pelvis 

    • However, you should suspect it if there are any of the above risk factors 

    • Regarding fetal position: 

      • Can be known by palpating the sutures

      • In babies that are OP, the posterior fontanelle will be felt

        • This feels triangular, as it is formed by the junction of the sagittal and lamboidal sutures 

      • This is in contrast to babies that are OA, where the anterior fontanelle can be felt (shaped like a diamond) 

      • Other methods = using transabdominal ultrasonography to figure out position, as rate of error for digital vaginal exam can range from 30-65% depending on the study 

    • An impacted fetal head is usually identified during the cesarean delivery: when you place a hand beneath the pubic bone to lift the fetal head, it is often difficult due to how low the head is.

      • Possibly cannot get hand around the fetal head to elevate 

      • Or it is difficult to elevate and flex the head due to position or how low the head is 

Why do we care about IFH? 

  • What are risks to mom? 

    • Other than it being really hard to elevate the head and delivering the baby, there are multiple risks to both mother and infant at this stage 

    • Increased risk of: 

      • Maternal hemorrhage 

      • Hysterotomy extensions 

      • Bladder injury 

  • What are risks to baby? 

    • Neonatal hypoxia 

    • Traumatic injuries 

  • Therefore, important to identify this and anticipate how to resolve IFH 

What should you do if there is a suspected impacted fetal head? 

  • Let others know what you are thinking 

    • Tell nursing staff, anesthesia, and neonatology 

      • This way, everyone is prepared 

    • Call for help if needed - if you need another team member to come in for assistance, it’s better to have them and not need them than if no one is there 

  • Position the patient accordingly 

    • We tend to favor positioning patient in a modified lithotomy position 

      • Can either frog-leg 

      • Or place in lithotomy, but bend legs down so that the hip joint is not flexed during the initial part of the case

        • Can use yellow fin stirrups 

        • Easy to then flex at the hip joint into dorsal lithotomy if needed  

  • Place your hysterotomy accordingly 

    • Especially if the patient has entered second stage, the lower uterine segment will be distended 

    • Hysterotomy should be placed relatively high to avoid inadvertent entry through the cervix or vagina 

  • Maneuvers to resolve IFH 

    • Now that you have encountered an impacted fetal head and done all the right things up until now. How do you get the baby out? 

    • Vaginal hand or “push” technique 

      • Someone wears sterile gloves and inserts hand into vagina to elevate the fetal head 

      • They do not remove the hand until the head has been disimpacted by the surgeon from above or if this method has failed 

    • Breech delivery or “pull” technique 

      • Another technique is to deliver breech

      • Surgeon will extract feet from hysterotomy and proceeds to deliver the rest of the fetus 

        • Studies in low-resource settings show that this technique resulted in decreased maternal hemorrhage, hysterotomy extensions, and infection when compared to the “push” technique  — comparison of different methods via systematic review and meta-analysis

    • Extending your hysterotomy

      • If extraction is still difficult, can proceed with extension of the hysterotomy either via a J or a T extension 

      • These are done usually with two fingers beneath the area that you wish to extend to protect the baby, then cut the uterus with bandage scissors 

      • Can lead to more bleeding and will result in longer repair, but may lead to increased 

    • Devices 

      • Fetal Disimpacting System or cephalic elevation device; Fetal Pillow

      • Basically an inflatable device that is placed into the vagina that elevates the fetal head!

  • One randomized controlled trial at BWH in Boston that showed that this device led to 23-second reduction from hysterotomy to delivery compared with other methods 

    • Patients all received the device in the vagina, but were randomized to whether or not the device was inflated or not.

  • Other techniques 

    • Other techniques have been described, but not as well studied as the push or pull technique 

    • One = shoulder-first method, where the shoulders are initially delivered through the hysterotomy, followed by traction placed on axilla to facilitate delivery of the body and subsequently the head (Patwardhan maneuver)

  • Last thoughts 

    • If an IFH occurs, and it is particularly difficult, especially if it leads to need for multiple maneuvers, remember to debrief! 

    • Both with the team - what happened, what went well, what could have been improved, and take home points 

    • Talk to the patient 

      • Often, this can be traumatic for both the provider and the patient 

      • The baby may need to go the NICU, there may need to be a hysterotomy extension 

      • Discuss what occurred with the patient and if maneuvers resulted in certain complications 

        • Discuss extensions, baby going to NICU

        • Discuss if need for future C-section if T incision has occurred